The present invention relates to methods for making organic thin film transistor array panels.
In general, flat panel displays, such as liquid crystal displays (LCDs), organic light emitting diode (OLED) displays, and electrophoretic displays and the like, include multiple pairs of field generating electrodes and an electro-optical active layer interposed therebetween. LCDs include a layer of a liquid crystal material as the electro-optical active layer, whereas, OLED displays includes an organic emission layer as the electro-optical active layer.
One of the pair of the field generating electrodes is typically connected to a switching element to receive an electrical signal, and the electro-optical active layer converts the electrical signal into an optical signal for displaying an image. Flat panel displays use thin film transistors (TFTs), which are three-terminal elements, as the switching elements, gate lines for transferring scan signals that control the TFTs, and data lines for transfer signals through the TFTs to pixel electrodes formed on the display.
Regarding the TFTs, active research is currently ongoing in the area of organic thin film transistors (OTFTs) that use an organic semiconductor material instead of a conventional inorganic semiconductor, such as Si. Because OTFTs can be fabricated by a solution process at a relatively low temperature, they can be advantageously applied, inter alia, to the manufacture of large-scale flat panel displays which would otherwise be limited as a result of a deposition process used in their manufacture. Additionally, OTFTs can be formed as either a fiber type or a film type, owing to the characteristics of the organic materials used, and accordingly, have received much attention as a core element of flexible display devices.
The methods for manufacturing an OTFT array panel are quite different from those used to make existing TFT array panels in terms of their structure and fabrication methods, and accordingly, it is necessary to provide manufacturing methods that minimize the adverse effects of the fabrication processes on the organic semiconductors during processing, while simultaneously improving the characteristics of the OTFTs.